Abstract Summary
This work is devoted to the analysis of the vibratory response of High-Speed (HS) multi-track railway bridges composed by short-to-medium simply-supported spans. The vibrational response of such struc-tures may be influenced by three-dimensional modes (first torsion and first transverse bending modes of the deck) and, therefore, the use of planar model may not be adequate. In particular, it aims to investigate the influence of three geometrical aspects usually disregarded in numerical models used to evaluate the Serviceability Limit State of traffic safety in such structures: (i) the deck obliquity, (ii) the presence and correct execution of transverse diaphragms at the supports, and (iii) the number of successive simply-supported spans weakly coupled through the ballast track layer. The influence of these aspects is ana-lysed from the correlation of a detailed numerical model and experimental measurements on an in-service High Speed (HS) multi-track railway bridge. From the reference model, a set of variants accounting for different levels of deck obliquity and dia-phragm configurations are envisaged and the maximum transverse acceleration over the platform is determined under railway excitation. The analysis is extended to bridges with an increasing number of successive spans covering the lengths of interest. Special attention is paid to the particular location of the maximum response and to the participation of modes different from the longitudinal bending one. Finally, a numerical-experimental comparison of a real bridge response under two train passages is presented for the straight and oblique models, and the response adjustment along with the actual bridge performance are assessed.
